Substance use and/or abuse by children previously diagnosed and treated with stimulant drugs for a hyperkinetic disorder is studied to determine whether these children use more drugs either in the form of medication and/or drugs of abuse when they become adolescents. Subjects are in grades six through twelve and include approximately 150 students identified as hyperactive, a random control group of 100 adolescents, and 50 behavioral equivalents who have a teacher rating on the Behavior and Temperament Survey equal to that of hyperactive children, but no evidence of parental or physician's concern about hyperactive behavior. Substance use data constitute the major dependent variable. Parents and children are asked about their use of beer, wine, cigarettes, hard liquor, marijuana, LSD, amphetamines and barbituates (with and without prescription), cocaine, herion, and glue. Behavioral characteristics and intellectual functioning are assessed by various rating scales. The subject's home environment and family characteristics are evaluated through interviews conducted annually with parents and census information. Data collected about the epidemiology of substance use provides a source of information for designing intervention methodology.